linux-kernel - Re: [PATCH 6/7] arch: __get_wchan() || ARCH

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Message-ID: <202110220910.0D3C298F73@keescook>
Date:   Fri, 22 Oct 2021 09:13:22 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org,
        juri.lelli@...hat.com, vincent.guittot@...aro.org,
        dietmar.eggemann@....com, rostedt@...dmis.org, bsegall@...gle.com,
        mgorman@...e.de, bristot@...hat.com, akpm@...ux-foundation.org,
        mark.rutland@....com, zhengqi.arch@...edance.com,
        linux@...linux.org.uk, catalin.marinas@....com, will@...nel.org,
        mpe@...erman.id.au, paul.walmsley@...ive.com, palmer@...belt.com,
        hca@...ux.ibm.com, gor@...ux.ibm.com, borntraeger@...ibm.com,
        linux-arch@...r.kernel.org, ardb@...nel.org
Subject: Re: [PATCH 6/7] arch: __get_wchan() || ARCH_STACKWALK

On Fri, Oct 22, 2021 at 05:09:39PM +0200, Peter Zijlstra wrote:
> Use ARCH_STACKWALK to implement a generic __get_wchan().
> 
> STACKTRACE should be possible, but the various implementations of
> stack_trace_save_tsk() are not consistent enough for this to work.
> ARCH_STACKWALK is a smaller set of architectures with a better defined
> interface.
> 
> Since get_wchan() pins the task in a blocked state, it is not
> necessary to take a reference on the task stack, the task isn't going
> anywhere.
> 
> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>

Nice, this looks good.

Reviewed-by: Kees Cook <keescook@...omium.org>

-- 
Kees Cook